TDA7293 amplifier IC ideas?

[Rodgre]

I just picked up a couple of TDA7293 100w amplifier ICs in hopes of fixing a SS Marshall that has a dead channel. I was wondering what I could do with the spare. Has anyone built an amplifier circuit based on the TDA7293?

That reminds me that I have a replacement amplifier chip for a Vox Pathfinder (probably my favorite SS amp) that might want to contribute itself to an amplifier project too!

Roger

[R.G.]

I messed with those a little bit.

Be careful with them. A single 7293 package cannot dissipate enough power for the 100W rating they claim. You need at least two of them, with the second one in the "slave output" mode they talk about so you can get enough heat out.

They are also sensitive to something about the power supply hookup. I can't remember all of it. It was on the rail in one of the hifi audio forums, so you might do a search on something like amplifiers with the TDA7293.

I satisfied my curiousity, generated some smoke, and when I had burned up about half of the ones I bought  I decided that I'd use LM3886s for power amp chips. For me, the LM3886 seems to be about bulletproof.

But, as they say, your mileage may vary. 

[Rodgre]

Thanks R.G.

That's about all I needed to hear.

I'll save this one for the next blown amp that I have to repair that uses one.

Roger

[anti-idiot]

I messed with those a little bit.

Be careful with them. A single 7293 package cannot dissipate enough power for the 100W rating they claim. You need at least two of them, with the second one in the "slave output" mode they talk about so you can get enough heat out.

They are also sensitive to something about the power supply hookup. I can't remember all of it. It was on the rail in one of the hifi audio forums, so you might do a search on something like amplifiers with the TDA7293.

I satisfied my curiousity, generated some smoke, and when I had burned up about half of the ones I bought  I decided that I'd use LM3886s for power amp chips. For me, the LM3886 seems to be about bulletproof.

But, as they say, your mileage may vary. 

how many LM3886s do yo use to make a 100w amp? how good does it sound?

[R.G.]

how many LM3886s do yo use to make a 100w amp? how good does it sound?

Two. That's about $10. However, the power supply for this is what takes all the money and time, not the chips.
Count on about 50W per LM3886. There are application-note designs from the maker of the chip for amps of up to 200W per channel.

It sounds very hi-fi or PA; that is, it sounds exactly like what you put into it.

Which leads us to some amp theory. Guitar amps are not reproducers of sound. They are producers of sound; they are part and parcel of the guitar sound itself.
The interaction of a tube amp with the signal source on the front end and the speakers on the back end are not like modern hifi amps. This leads people to criticize solid state guitar amps as not being what they expected when they started to listen to it.

However, there are ways to make SS amps sound more like the real thing. We know this is possible, as almost all actual listening to guitar amps is done in fact by recording the guitar amp and playing the recording back through hifi SS amps. So it is *possible* to make a SS amp sound like a guitar amp by some means, even if that is a difficult one for the guitarist. Even at concerts, miking up a small guitar amp into the PA system is how most people hear guitar.

And we have part of the solution in our effects (for natural sounding distortions) and our speaker emulators to simulate the actual frequency response of the playback.

It's not easy to make an SS amp sound exactly like a tube amp; we already know this (duuuhh) because otherwise tube amps would be a footnote in history from the 1960s. But they can be very satisfying in themselves.

Additional reading:
http://sound.westhost.com/project27b.htm
http://sound.westhost.com/project27.htm

[Ben N]

Be careful with them. A single 7293 package cannot dissipate enough power for the 100W rating they claim... I satisfied my curiousity, generated some smoke, and when I had burned up about half of the ones I bought  ...

Why am I not surprised that Marshall uses them?

[anti-idiot]

Be careful with them. A single 7293 package cannot dissipate enough power for the 100W rating they claim... I satisfied my curiousity, generated some smoke, and when I had burned up about half of the ones I bought  ...

Why am I not surprised that Marshall uses them?

they're livin' by their name... such a shame